Online financial transactions titan PayPal on Thursday began letting merchants worldwide take payments using smartphones in a direct challenge to startup Square. The PayPal Here system uses a triangle-shaped \"dongle\" card reader that plugs into mobile devices to let people make purchases. PayPal Here software also lets shopkeepers take payments by snapping a picture of a card with a smartphone instead of having to swipe it in the dongle. \"There is a lot more than the triangle shape of this device,\" PayPal mobile vice president David Marcus said while unveiling the new service at a press event at San Francisco\'s famed Ghirardelli Square. \"No business will ever have to say they can\'t accept a form of payment.\" The service from eBay-owned PayPal is a spin on one offered by startup Square, a brainchild of Twitter co-founder Jack Dorsey.